NaCl-assisted synthesis of MoS2 films: Large area fabrication with evidence of phase shift

Abstract

Two-dimensional (2D) nanomaterials have shown unique electrical and chemical characteristics essential for the enhancement of electronic and optoelectronic devices. Large-area fabrication of 2D materials like MoS2 is challenging due to poor nucleation and vertical multilayer growth. In this study, we employed wafer-scale CVD with gaseous precursors for MoS2 to facilitate large-area deposition and utilized NaCl to assist nucleation control. Precise control of the nucleation with NaCl has significantly increased the grain size of MoS2 from about 1–2 nm to 300 nm. However, a phase shift in MoS2 thin films from semiconductive 2H to metallic 1T phase was observed due to the Na intercalation. As a result, a shift in lower binding energy occurs in XPS analysis. Our findings contribute to the comprehension of phase transition phenomena in MoS2 thin films and further advancement in the synthesis techniques of MoS2 thin films within wafer-scale deposition environments.